It can take up to about 12 hours for the anesthetic to wear off. Did the vet give you any take home instructions? How awake was she when you first brought her home. It's normal to see "flopping" when they are first waking up, but I've yet to see a cat pant from anethetic. You might want to call your vet and see what kind of anesthetic and induction they used - perhaps she had an allergic reaction to it?

I really hope she feels better!