I was thinking that Hoover had a different color for each year or period, but as I attempted to assemble the following list from various Vacuumland threads that doesn't seem to be the case--at least not all the time.
Anyway, here are some of the Hoover models and their colors over the years. Feel free to make additions or corrections:
Partial List of Hoover Colors by Sales Years (1954-1992)
CONSTELLATIONS
SERIES ONE
1954-55: Model 82 (Pearl White/Blue)—matched Model 63 (1953-56)
1955-56: Model 84 (Sandalwood/Taupe)—matched Citation Model 64 (1956-57)
1955-56: Model 84B (Sandalwood/Taupe)—“ “ “
1956-57: Model 85 (Pearl White/Heather Rose)—matched Convertible Model 65 (1957-59)
SERIES TWO
1958-59: Model 86 (Antique Gold for 50th; Porcelain Blue/Navy Blue)—matched Convertible models 65, 68
1958-60: Model 87 (Garland Green/Pearl White)—matched Convertible Model 66
1960-62: Model 88 (Fawn/Pearl White)—matched Convertible Model 67
1962-64: Model 434 (Canton Red/Pearl White)—matched Convertible Model 574
1964-66: Model 444 (Bittersweet Orange)—matched Convertible Model 34
1966-68: Model 454 (Tropic Island Green)--matched Convertible Model 36
1968-70: Model 843 (Autumn Gold/Seal Greige or Taupe—tilted)--matched Convertible model 1060
1970-75: Model 858 (Pumpkin/Seal Greige or Taupe; Poppy Red/Oyster White)--matched D-A-M model 1120
SERIES THREE
2006-09
CONVERTIBLES (through 1980)
*“Special” models were basic versions with no headlight, step-on switch, snap on bag
1957-59: Model 65 (Heather Rose/Pearl White)
1958: Model 65 (Antique Gold/White--for 50th Anniversary)
1958-60: Model 31 Special (Shades of Garland Green)
1958-60: Model 66 (Garland Green/Pearl White)
1961: Model 564 (Antique Gold/Pearl White) – Limited Edition for Promotion
1961: Model 68 (Porcelain Blue/Pearl White) – Deluxe Limited Edition to introduce vinyl handgrip
1960-62: Model 67 (Fawn/Pearl White)
1962: Model 574 (Canton Red/Pearl White) – Limited Edition for Promotion
1961-64: Model 69 (Neptune Green/Pearl White)
1961-62: Model 32 Special (Clover Pink/Pearl White)
1962-64: Model 33 Special (Dusky Lavendar/Pearl White)
1963-69: Model 334 Special Commercial (Porcelain Blue/Pearl Gray)
1964-66: Model 70 (Delft Blue/Pearl White)
1964-66: Model 34 Special (Bittersweet Orange/Pearl White)
1964-66: Model 35 Special (Lt. Venetian Gold/Pearl White)
1964-68: Model 584 Special Semi-Commercial Promotional (Garland/Pearl or Seal Greige)
1966-68: Model 36 Special (Tropic Island Green/Pearl White)
1967-70: Model 704 Promotional (Persian Gold/Pearl White or Shades of Seal Greige)
1967-70: Model 714 Promotional (Sunset/Shades of Seal Greige)
1968-69: Model 1010 Special (Spring Green/Shades of Seal Greige)
1968-69: Model 1060 (Autumn Gold/Shades of Seal Greige)
1970: Model 704-01 Promotional (Persian Gold/Shades of Seal Greige--w/cord reel)
1969-71: Model 1070 (A Line) (Marine Blue/Shades of Seal Greige)
1969-71: Model 1020 (A Line) (Spring Green/Shades of Seal Greige)
1969-71: Model 719 (B Line) (Delft Blue/Shades of Seal Greige)
1969-71: Model 589 (B Line) (Victorian Rose/Shades of Seal Greige)
1970: Model 706 Deluxe Promotional (Shades of Seal Greige/Persian Gold)
1969-75: Model 344 Commercial (Porcelain Blue/Lt. Seal Greige or Taupe)
1969-71: Model 348 Commercial (Porcelain Blue/Lt. Seal Greige or Taupe—with grounded plug)
1971-73: Model 1030 (A Line) (Bali Green/Shades of Taupe)
1971-73: Model 1076 (A Line) (Ceylon Yellow/Shades of Taupe)
1971-73: Model 593 (B Line) (Surf Green/Taupe)
1971-73: Model 728 (B Line) (Camilla Pink/Lt. Taupe)
1971-75: Model 707 Promotional (Spring Green/Garland Green)
1972-75: Model U4001 Promotional-K-Mart (Persian Gold/Taupe; Copper Orange/Taupe; Shades of Taupe)
1973-75: Model U4003 (A Line) (Shades of Taupe)
1973-75: Model U4005 (A Line) (Stellar Blue/Taupe)
1973-75: Model U4007 (A Line) (Goldtone/Taupe)
1973-75: Model U4009 (A Line) (Copper/Taupe)
1973-75 Model U4017 (B Line) (Shades of Taupe)
1973-75: Model U4019 (B Line) (Bali Green/Taupe)
1973-75: Model U4021 (B Line) (Powder Blue/Taupe)
1974-75: Model U4027 Promotional (Stellar Blue/Taupe)
1974-76: Model U4047 Promotional (Sunset Orange/Taupe; Flame Orange/Taupe)
1975-77: Model U4057 ( A Line) (Leichen Green/Oyster White)
1975-77: Model U4059 (A Line) (Maple Sugar Tan/Oyster White)
1975-77: Model U4061 (A Line) (Poppy Red/Oyster White)
1975-77: Model U4063 (A Line) (Goldtone/Oyster White)
1975-77: Model U4037 (B Line) (Goldtone/Oyster White)
1975-77: Model U4039 (B Line) (Poppy Red/Oyster White)
1975-77: Model U4031 (C Line) (Goldtone/Oyster White)
1975-77: Model U4033 (C Line) (Poppy Red/Oyster White)
1975-77: Model U4053 Promotional (Poppy Red/Oyster White)
1975-77: Model U4075 Promotional (Sea Blue/Oyster White)
1975-77: Model U4087 Promotional (Forest Green/Oyster White)
1976-78: Model U4089 Promotional (Goldtone/Oyster White)
1976: Model U4085 Promotional-Bicentennial (Sea Blue/Oyster White)
197?: Model U4091 Promotional (Persian Gold/Oyster White)
1976-78: Model U4095 Promotional (Flame Orange/Oyster White)
1977: Model U4099 Promotional (Sea Blue/Oyster White)
1976-78: Model U4111 Promotional-Denim (Denim Blue/Oyster White)
1976-78: Model U4113 Promotional (Goldtone/Oyster White)
1976-78: Model U4115 Promotional (Poppy Red/Oyster White)
1976-78: Model U4163 Promotional (Powder Blue/Oyster White)
1977-80: Model U4101 (A Line) (Mint Green/Oyster White)
1977-80: Model U4103 (A Line) (Sea Blue/Oyster White)
1977-80: Model U4107 (A Line) (Camel Tan/Oyster White)
1977-80: Model U4109 (A Line) (Rust Brown/Oyster White)
1977-80: Model U4123 Promotional (Poppy Red/Oyster White)
DIAL-A-MATICS
(*Power Drives)
1963-64: Model 1100 (Sunset Orange/Pearl Gray/Deep Mist Gray)
1964-65: Model 1110 (Peacock Blue, Pearl Gray and Deep Mist Gray)
1964-65: Model 1120 (Pumpkin Orange and Seal Greige Light, Medium, and Deep)
1965-66: Model 1130 (Spring Green and Taupe Light, Medium and Deep)
1965-66: Model 1136 (Flemish Blue and Taupe Light and Medium)
1966-67: Model 1140 (Marine Blue and Seal Greige Light, Medium and Deep)
1966-67: Model 1149 (Bali Geen and Taupe Light, Medium and Deep)
1967-68: Model 1151 (Flamingo Orange and Seal Greige, Light Medium and Deep)
1967-68: Model 1157 (Ceylon Yellow and Taupe Light, Medium and Deep)
1969-70: *Model 1170 (Seal Greige Light, Medium and Deep)
1970-71: *Model 1176 (Persian Gold and Seal Greige Light, Medium and Deep)
1971-72: *Model 1178 (Taupe Light, Medium and Deep)
1972-73: Model U5007 (Light Copper and Light Taupe)
1972-73: Model U5007-001 (Cinnamon and Oyster White)
1973-74: Model U5015 (Persian Gold and Oyster White)
1973-74: Model U5017 (Lichen Green and Oyster White)
1975-76: *Model U6003 (Sunset Orange and Light Taupe)
1975-76: *Model U6003-001 (Poppy Red and Oyster White)
1976-77: *Model U6007 (Antique Copper Shadow and Light Taupe)
1976-77: *Model U6039 (Sea Blue and Oyster White)
1977-78: *Model U6041 (Luggage Tan and Oyster White)
1977-78: Model U6049
FLOOR-A-MATICS
(*w/Headlight)
1967-69: Model 3600 (Flamingo Orange/Taupe Light and Medium)
1969-71: Model 3610
Model 3614 (Sky Blue/Taupe Light and Medium)
*Model 3616 (Ceylon Yellow/Taupe Light and Medium)
Model F5019 (Rust Brown)
CONCEPT ONES (Power Drives)
Older Style
1978- 86: Model U3101 (Jamaican Blue And Horizon Blue)
1978-86: Model U3103 (Rust Brown And Pale Honey)
1979-86: Model U3105 (Holly Green Oyster White) ( I have this one )
Model U3107 No Info.
1978-86: Model U3109 (Rust Brown and Pale Honey)
1988-91: Model U3109-100 (Pastel Beige And Burgundy)
1988-91: Model U3223 (Jamaican Blue and Horizon Blue)
Model U3225 No Info.
1983-87: Model U3305 (Mist Gray And Light Gray and Black)
1985-87: Model U3307 (Slate Green And Black)
1987-91: Model U3311 (Rust Brown And Oyster White)
Newer Style
1987-92: Model U3315 (Blue Shadow And Pastel Beige)
1987-91: Model U3315-070 K-Mart Exclusive (Blue Shadow and Pastel Beige)
1987-91: Model U3317 (Burgundy And Pastel Beige)
1987-? Model U3319-900 (Cashmere Blue And Blue Shadow)
1988-92: Model U3329 (Slate Green And Black)
1989-91: Model U3335 (Blue Shadow And Pastel Beige)
1988-92: Model U3339 Sears Model (Camargue Blue)
1991-92: Model U3341-900 K-Mart Model? (Dark Hunter Green and Black)
1991-92: Model U3345-900 Sears Model (All Black)
CONCEPT ONES (Non-Power Drives)
Older Style
1978-86: Model U4201 (Jamaican Blue And Horizon Blue)
1978-86: Model U4203 (Rust Brown And pale Honey)
1979-86: Model U4205 (Holly Green And Oyster White)
1987?: Model U4209 (Rust Brown And Oyster White)
Newer Style
1986-1990?: Model U4219 (Cashmere Blue And Blue Shadow)
CONCEPT TWOS (Power Drives)
Older Style
1983-86: Model U3301-030 (Mist Gray And Light Gray And Black)
1983-86?: Model U3303-030 (Mahogany Brown And Honey Beige)
1985-87: Model U3309 (Slate Green And Black)
Newer Style
1987-91: Model U3321 (Burgundy And Pastel Beige)
1987-91: Model U3323 (Cashmere Blue And Shadow Blue)
1987? : Model U3331 (Slate Green And Black)
CONCEPT TWOS (Non-Power Drives)
1983-86?: Model U4211 (Mist Gray And Light Gray And Black)
1983-86?: Model U4213 (Mahogany Brown And Honey Beige)
?? : Model U4217 (Slate Green And Black)
CONCEPT ONE (Commercial)
??: Model U7097 No. info.