Dave;
Shop around for spares.
Many owners like the Silver/Alu look and sell the original colour parts off all the time for very little. Personally, I find the Alu on Alu look about as exciting as a church pew, but to each his own. Therein becomes your source of colour change.
You will find there are different colour shades available, some quite rare and no longer produced. Try EBAY and poke around on the German, Swiss or French sites.
Changing them is quite simple, at least the front plates, which is primarily what is viewed when looking at the speakers. As simple as small Torx screwheads. ( The top and bottom elliptical pieces are double-taped on and slightly more work ).
You can have Blue for Winter, Red for Christmas, Green for Spring, and Gold when you pay your taxes !