Is is possible to change the background color of a draggable once it has been dropped ?

Is is possible to change the background color of a draggable once it has been dropped ?

 
I got this small project im working on.
 
Everything is working great.
 
Im trying to add a function where once the draggable element as been dragged and drop into the calendar, its background color changes.
 
Is is it possible ?
 
I try to mess with the stop event but.....
 
Thanks in advanced.