The Official Site Homing Beacon talks about Episode III costumes. Here's a clip of the action to encourage you to subscribe yourself:
Anakin Skywalker clearly has the most profound transition from the prequel to the original trilogy, but the evolution of his Jedi robes from Attack of the Clones to his garb in the new installment is more understated than his future look of dark armor. "We changed his cloak shape, and gave him a new slightly more Jedi-like cloak this time," says Biggar. "We changed his colors, and we darkened them all down, hinting at what he's going to become. Although he was quite dark brown before, there were some lighter aspects. This time, we've really taken shades of dark brown to give him a dark outline even though he's still a Jedi."
Though Senators Padmé Amidala and Bail Organa are absent from the original films, they continue to evolve Episode III, building upon their looks from the previous chapter. "In Episode I, Padmé was very formal and very ceremonial, and that became slightly relaxed for Episode II. In Episode III, we see her in a couple of business-like -- but not heavily ceremonial -- costumes, so generally her look is softer, and we get a chance to see her in a more relaxed state. I think even more relaxed now than she was in Episode II -- softer, more feminine," explains Biggar.
"Though we saw Bail Organa in Episode II as a Senator, George wanted him to look slightly more high tech in a way," she says. "We ended up using more metal pieces in his costumes. He has a high-tech metal comlink, and his ceremonial Senate costume has a beautiful metal collar piece."
