I am a front end web developer. I tend to mostly deal with code but do, from time to time, have the opportunity to create graphics. I notice the designers I work with are able to talk in great detail about the images/designs they create. They can give meaning to why a button looks a certain way or the feeling behind their design decisions. What I am wondering is, as I have done some searching with no luck, are there any books on how to talk/describe this way? I am finding it hard to describe my question but I am looking for info on how to better 'sell' a design or justify a design decision.
Backing up layout decisions from studies/stats is fine, justifying those things can be backed up with numbers. But, it is more the whys and whats of color decisions and the purely visual side of things.
Update: Any links to good books would be a great help - typography, color theory, etc.