Uhm, youve only had your cham for a day. She's dark because she's REALLY stressed out. I wouldnt handle her unless you absolutely have to, as handling will only make the situation much much worse. She's going to be aggressive, veils are very territorial and tend to be aggressive anyway.
Chams are not really pets that can be handled. I cant stress this enough. Lots of unnecessary handling will only stress them out, possibly shortening their lifespan. My chams are ONLY handled to go outside for real sun, and to clean their cages. Occasionally George goes in the shower. I NEVER handle my female Jacksons because it really freaks her out. its just not something that's good for them long term. You may think its great "hey, what a cool animal i have, i need to touch it!" but its really upsetting to them. Consider that when you go to handle her.
As far as her stress, put a towel or sheet over the cage to give her a visual barrier, at least for a few days. Make sure she's eating and drinking, keep her misted (3 x daily minimum), and leave her alone. Thats the best thing you can possibly do for her.
Hope that helps,
Jamie
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Jamie A. Stine and the Gang:
0.1 Jacksons Chamelions (Clank) (we miss you, ratchett)
1.0 Veiled Chamelion (George)
1.1 Bearded Dragons (Lancelot & Guenivere)
1.0 Giant Frog Eyed Geckos (Peanut Butter)
0.0.1 Albino Pac Man Frog (Hermann)
0.1 Borneo Short Tailed Python (Ezmerelda)
0.1 Red Tailed Boa (Buffy)
1.0 Short Tailed O'possum (Jethro)
1.0 Greyhound (Hank)