Here's a pretty good reference pic
Description:
Penny looks like a pretty tough girl. She has short brown hair in a pixie cut and a surprisingly attractive face, usually smiling brightly. Her body, when visible, is toned and muscular but not unattractively so. She has fair skin with a few random freckles, and no piercings or tattoos at all, not even her ears. She appears to be in her early twenties, and stands five and a half feet tall or so.
She wears biker leathers almost all the time, and a backpack big enough to carry a laptop and college books. Under the leathers she wears a tee-shirt and jeans most of the time, and carries herself with confidence.
Penny "Gadget" Simmons, Hardware - Analytical Genius (Heroes Unlimited)