I try to make 3/4 of each general's element like any other element of his type, with the rest a small "general's vignette". This both clearly distinguished them as generals, makes it easy to see what their element is and looks good.
The vignette-part of one of my Carthaginian cavalry generals who is receiving a Numidian messenger.
Carthaginian chariotry general determinedly charging the enemy while his entourage on both horse and foot is trying to keep up.