My brother-in-law and I had the same cocktail at the Wynn. The bartender told us it was equal parts pomegranate juice, pineapple juice, and light rum. He put the contents over ice and shook them in the cocktail shaker and served in a martini glass. I can't remember the drink's name, but I decided to call it the Parasol Down, since this is the name of the cocktail lounge where the drink was served.
P. S.
I made it at home and I added a bit more pomegranate juice, which seemed to make the color look more like what was served in the lounge.