If we're going to discuss wether snakes "see" heat or not, we pretty much have to define what it means to see. For my money if the heat pits feed into the vision centers of the brain, I could call that seeing. Just because they strike accurately at heat sources doesn't mean they "see". It just means they have accute range and direction fidelity in their heat detection.
The other thing to look into is this: are the heat pits "heat sensors" that can feel heat like our skin can, only more sensitive, or are they infrared detectors. Infrared is electromagnetic radiation (like light) given off by objects based on their temperature. If heat pits are the former, there's no way it can be vision. If it's the latter, you could make the argument that it is seeing.
In any case, the quality of snakes vision certainly varies a lot between species, but I have no idea about color etc...
1 adult bull snake: "Dozer"; 1.1 juvenile bull snakes: Oscar and Phoebe; 3 baby red-sided garters; 1.1 macklot's pythons