I have done a few cakes for 20/21/22 year old girls recently & I also consulted my 22 year old daughter, who helps with the decorating, when home from university.
You certainly have not been given enough suggestions/ideas.
Like mandysue says, just pink is quite ridiculous.
I was asked to do a cake in feminine colours but definitely not girly stuff for a 20 year old. She was an outdoor girl, so I did a combination of flowers, butterflies & ponies, which worked very well. She was delighted with the results.
Hearts can also work quite well, either combined with flowers or by themselves.
But I really think you must be given some more ideas what the girl would like.
As my daughter says, she loves pink but would be quite horrified at a cake with 'girly stuff such as make up on it'.
Now her best friend of the past 15 years would love a cake like that.
Girls of that age have very definite ideas what they do & do not like.
It also would not hurt to tone down the pink a bit with touches of other colours.
But basically, you must be given more ideas/suggestions before going any further.