I think that the only non-black lenses from anyone but Canon are quite large and unique ones and not ones that are essentially duplicate focal length of cheaper lenses but with higher quality and faster. (Ie,
nobody else makes their 70-200mm in anything but black.) Heck, Canon even paints their 1.4x multiplier white! How much heat can that little thing absorb?
Pentax did make a silver 300mm F4.5 in the '90s, I can't think of any others off the top of my head but I think their 600mm or so was silver as well. I may end up with a silver 31mm F1.8, but that's not painted, it's bare aluminum, and you can also get it painted black - that is definitely a style choice.
I think that Nikon had a couple fast long primes in gray, but I don't remember any details - and I can't remember ever seeing any such lenses from Minolta, Olympus, Sigma, Tamron, Tokina, Zeiss, Leica, Voigtlander, Mamiya, etc, etc, though I'm certainly not an authority of those companies or their lens histories.