Bacchae
Since Dionysus is half mortal, he has to work very hard to prove himself that he IS in fact a god (lines 40-41), and I think that reflects in his followers/cult. They bang drums, sing praises of Dionysus, and they all dress the same with head pieces. I think that since they are dressed a certain way and make so much noise, with their singing, tambourines, and drums, they intend to draw attention to themselves, which in turn draws attention to Dionysus. As he said earlier, the city needed to learn that he was the son of Zeus, even if he needed to use force, (lines 39-41) and the force he uses is his cult.