They can be pretty riled up after getting so stressed at the vets. Just give her some alone time in a quiet place and let her calm down
Okay, some advice on preventing this issue. I work as a vet tech at a cats only clinic so I've seen it all. Now some cats are so aggressive at the vet that sedation will always be required. Still others are so aggressive, you can't even get to them to sedate them (without the risk of losing several fingers). Always know, your cat is not the worst!!!
Usually a lot of the problem is what I call the "wind up". They see the carrier, are shoved into it unceremoniously, then have to ride in the car, and then brought into the vet clinic that's full of loud noises and unfamiliar scents. If I was a cat, I'd get a little POed too. So work on taking as much stress as possible out of every step.
1) Leave the carrier out at home. Let your cat get completely used to it, putting in favorite toys/blankets/etc. That way it isn't just seen as "Carrier=vet"
2) For actual vet trips, spray Feliway in the carrier before departing. Also invest in some DryFurs (a little pad to put in the carrier that's soft and prevents slipping and sliding in the car, towels just bunch up).
3) If possible, find a cats only clinic if your baby isn't used to dogs. That can lower the stress level tremendously. Also, a cats only clinic will have much more experience handling aggressive cats and know the best way to handle the situation.
4) Ask your vet if you can be placed in a room immediately and seen ASAP. Try getting the first appointment of the day. The longer your baby has to wait in a strange environment, the worse it gets.
5) Another thing that can do wonders is board your cat at your vet for a few days (if they have nice, cat friendly boarding available). Even aggressive babies usually warm to the staff at least a little after 2-3 days.
Anyway, sorry it was long!! Hope it helps!