OK. Although probably enough has been written here.. I'll just add my two cents, cuz that's what I do;-)
"She's game for anything" wouldn't be my choice for even an informal assessment of a potential employee.
The statement itself can or cannot be "anstößig"... completely dependent upon the way it's said.. but because this is about a woman and not a man.. and the fact that it can lead a dirty-minded reader to go off in a dirty-minded direction, well, I'd say it's just wiser to just leave it in the drawer. (No, no, I didn't say 'drawers'!)
"She's up for anything" doesn't seem to evoke a possible sexual innuendo as easily, but still, I'd go with something else that actually describes her personality, such as bits and pieces of the following string of ideas, perhaps... nach Belieben:
"She's a dynamic, fun-loving, gregarious, outgoing young woman who knows equally well how to work and how to relax and have a good time with others. She shows enthusiasm and initiative and enjoys getting things going in a group of people. She's excellent at engaging those around her to undertake projects and to get tasks completed. Moreover, her former employers say she seems to have a special knack for motivating others without coming across in any way as bossy or pushy (or: overbearing).... She's not the type to sit back and wait for others to come up with all of the ideas (or make all the calls).
Jeez! Where is this young woman??? I need her here ASAP!! (Can she tutor me in German, too?)