Is it a wild caught or a captive bred? And I completely agree with eunectes4, make sure it's enclosure is up to anaconda habitats, let it slowly work it's way up to you when holding, and if there is a lot of traffic, make sure to cover the front or do something to just keep the snake happy.... What I did for a wild caught anaconda was I got her out ***SLOWLY*** and when he or she is out, I would keep a shirt out or blanket, and let her crawl into it, to make her feel secure... The first few times I wouldn't keep her out for a really long time, and try not to get her/him out anymore than one to two times a day... Another trick I have learned was that whenever using gloves (this is just something I do, it might not work, but who knows) is to find one kind of soap, and I would soak the gloves in water with the soap, until the smell of the soap is in the glove... Whenever she isn't quite as snappy after awhile, whenever you take the gloves off, wash your hands with the same soap, and the anaconda might be more prone to your scent... Overtime she will get used to you (I would hope, anacondas can be very... wishy-washy) I hope any of this helps!!! I wish you the best!
-Ben