All the camos have their own .txt file like for example Hexagon Autumn
And as you can see it has properties like texture, is it adaptive and more interestingly color. The color can be changed while the game is running with programs like Cheat Engine for example.
While the game is running we search for the GUID (f7bfb1ccf8a2d04b811b341c61a08b77 for Hexagon Autumn as you can see) as an array of bytes.
View the results in memory (In CE right-click->Browse this memory region) until you see something like this. Usually the right one starts with 04xxxxxx.
4th row has the pointer to the texture which you can change to something else if you'd want to (For example the DICE camo). Next 4 rows are the RGB(A?) vectors.
Here's an example of Color1 set to red, Color2 set to green, Color3 set to blue and Color4 set to white.
But ofc the result wont be exactly pretty:
Here's a link to a .rar containing the camo .txt files if anyone's interested: http://files.1337upload.net/Camo.rar
oh and if it somehow wasn't clear enough from the name "Cheat Engine", don't do this on a punkbuster server.