In the pics we’ve seen of Mader in SB, she’s not green though. She is wearing a GIANT green pendant (looks like the one from OZ the G and P) that might be masking her green skin, which means she can turn it on and off, so to speak.
Interesting theory. Sort of like a magic cloaking device. Or if you’ve watched Angel, Jasmine was like that. She was beautiful on the outside but in reality, a giant, ugly thing with bugs.