The fact that she purposely is touching shoulders with you probably means one of two things she's comfortable with you and she likes you. Try to flirt with her and see how she responds. If she responds positively ask to hangout. You can always propose to hangout with you and someone else in you friend group since you guys seem to have the same friends. Then say that the friend can't come but that it would still be fun if you did something just the two of you.