In the 1950's and 60's, many parts were the same colour as the cleaner, but by the 70's white led the way as it was cheaper and easier to have one generic colour. By the 80's, black was looking more up to date. When I was ordering spares back in the day, non genuine pattern parts like tools and hoses were always available in black, white, or brown to suit the customer, but that was as good as it got.
Colours always go in and out of fashion on anything in life, but on vacuum cleaners it strikes me that the manufacturers always seem to forget that making just one colour for all tools across all of it's ranges is still the cheapest way to do it. Look at Dyson. Even they eventually latched onto this and began making everything in grey. Took them long enough, mind you.