For reference, here's the actual comic sequence:
The snap itself doesn't have any real meaning (in the comics of the movie, really) - it's just an action that shows how effortlessly he's wielding infinite power. No buildup, and it's not alluded to in advance or referenced later.
With that in mind, I'd avoid something that feels ominous - like "WITH A SNAP OF MY FINGERS" - which isn't in-line with the intent. "IN A SNAP" is a lot closer if we're not happy with simply "SNAP!"