I have a MULTI cat household also with all sorts of different color bombos. I do have a dilute all over peach/sand colored male that i rescued at about 4-5 months. He had been kicked(********!) by some horrid little child who broke his pelvis. Well, during treatment and recooperation he and i worked out a little code thingy. I would have to lift him and hold him in the litter box and i could tell from his meow what he wanted. He has recovered with a wobbly rear gate, and it spoilt beyond belief(he deserves it), but i always thought he was a smart cookie because we were able to "communicate" with each other successfully. I also have a female calico whos mother is an Apple head Siamese. "Cali" is very bright and intelligent. She taught herself to pee in the toilet(hasn't learnt to flush yet though)
she taught "ME" how to play kitty fetch. She has the fiery temperament of a red head and the intelligence of the Siamese(she can be a real little cow too). Now i have a large all black male who i can just see the intelligence in his eyes and he is a stinker too. Another large all black male has large "owl" eyes which give him a bit of a retarded look, but he is just mellow and laid back, i call him my surfer dude kitty. I dont necessarily think intelligence depends on the colors as much as the breed of cat, that being said i have alley cats who if human could work at NASA.
Mikala