Just give her time. She'll come out on her own. Some cats a like that. Whenever I get a new cat, I always isolate them in a room with their litterbox, food, water, toys and a radio playing. Eventually (after a couple of days, or whenever I feel comfortable) I let the cat out to explore the surroundings. I ALWAYS make sure I'm at home when I do this. Cats are strange creatures of habit. They don't like change. It could be that your kitty feels overwhelmed by everything (surroundings, new home, new human, etc.). Just give her time.

One suggestion would be to sit on the floor at her level and throw her treats. She may come to you, she may not. Also, when talking to her, whisper and slowly blink your eyes while looking at her. This will let her know that everything is okay and you're not a threat.

Good luck and welcome to Pet Talk!!!