Most potions, if any at all, in the core rules don't have descriptions like that. I don't really know of another source that does. I wouldn't mind having descriptions though.
As anyone, who's played crpgs knows, all healing potions are red.
Cure Light Wounds come in thin little vials.
Cure moderate wounds are a little thicker.
Cure serious wounds potions are large and bulbous and barely fit into the potion belt.
[Ducks and dodges out of the way of the vegetables]