The current listing of feline coat colors is pretty limited and quirky, especially when it comes to dilute colors or pointed cats (Siamese type colors), requiring users to pick a "ehhh...close enough" option. For my own shelter, we mainly resort to using the color details field to type the actual color. When I mentioned this a while ago it was mentioned that I should submit a feature request, and now I'm finally doing it! A more thorough list is proposed below. Hopefully I didn't forget anything obvious.

Black
Black & White
Black Tabby
Black Tabby & White
Blue/Grey
Blue/Grey & White
Blue/Grey Tabby
Blue/Grey Tabby & White
Red/Orange
Red/Orange & White
Red/Orange Tabby
Red/Orange Tabby & White
Buff/Fawn
Buff/Fawn & White
Buff/Fawn Tabby
Buff Fawn Tabby & White
Brown/Chocolate
Brown/Chocolate & White
Brown/Chocolate Tabby
Brown/Chocolate Tabby & White
Smoke
Smoke & White
Smoke Tabby
Smoke Tabby & White
Calico
Calico Tabby
Dilute Calico
Dilute Calico Tabby
Tortoiseshell
Tortoiseshell & White
Tortoiseshell Tabby
Tortoiseshell Tabby & White
Dilute Tortoiseshell
Dilute Tortoiseshell & White
Dilute Tortoiseshell Tabby & White
Seal Point
Seal Point & White
Blue Point
Blue Point & White
Flame Point
Flame Point & White
Lilac Point
Lilac Point & White
Lynx Point
Lynx Point & White
Tortoiseshell Point
Tortoiseshell Point & White
Chocolate Point
Chocolate Point & White
White

These are still just generalizations, but I think most cats should be able to fall into one of these categories.