But you might want to consider a 12ga. You can load or get loads that are just as soft. If she takes to the game, she'd want a 12ga anyways and if she doesn't it will probably be easier to sell.
Here are some good choices for women's trap guns:
Though not a semi-auto, the Browning BT-99 Micro
is a good choice. I've recently seen the BPS Pump in a Micro Trap version available too.
The Beretta AL391 Urika is available in a Trap version (12ga) or a Parallel target version (20 or 12ga).
Whatever you do, get the gun fitted for her so that the recoil doesn't hurt/bruise her. She'll be more likely to enjoy the game.