Can I get a cash refund on a mattress that I just ordered?

I just paid money for a mattress at Mattress Discounters. I have decided that there is mattress at a different store that I want more. I'm looking over the paperwork for the purchase I made and it says all sales are final. Well, I just paid my money tonight and the item is not due for delivery until next Saturday. If I call in the morning do you think I'll be able to cancel the order? I don't even think the salesman has had time to contact the factory at this point.