Don't panic-- you can do a couple of things...
1) Recruit an art student at your school to direct the process and get a couple of sisters to help paint that he will supervise. Any fraternity friends who are good at art? Make sure to send a nice thank you and maybe a small gift-- heck-- these guys love serenades and those are free!
2) Get yourself an overhead projector. Have the artist draw what you need on transparency, and make it a sort of color by number. Hang your sheet or tarp on the wall and aim the projector-- sketch in your design and paint.
3) Talk to your adviser, stat!
She will be able to help you.
Pi Love