This is not legal in any state in the U.S. (Including Nevada.) Gambling of any kind is only legal if it's run by the state (lotteries), businesses with good connections who pay lots of taxes (casinos) or, in very special cases, churches (bingo and door prizes).
That's not to say that every unlawful gambling event is raided by the authorities and its participants prosecuted. There's too much of it for them to get it all. But if you want to have a prayer of being winked at and allowed to have your little game, you'd better give out a whole lot more than 60 percent of the take to the winners. Keeping 40 percent is, in all likelihood, more greedy than even the games run by gangsters. Casinos get by on just a couple of percent and even churches are more generous than you are.
Take your cues from the stuff you see people getting away with. The office football pool: 100 percent of the money taken in goes to the winners. The Friday night poker game: Even most of them are zero-sum games, but if the house takes anything it's just a pittance to pay for the refreshments so the host breaks even. You can't make a profit off of private, off-the-books gambling and get away with it.
You also need to keep the stakes low. The cops aren't going to bother busting a football pool with a $250 prize or a poker game in which the big winner goes home $100 richer. You get up into the quadruple digits, you're asking to get busted.
I am not in any way endorsing your idea, I'm just giving you the facts as I know them. What you're thinking of is pretty much what gangsters call "the numbers racket." As illegal gambling goes, this version is very much frowned upon. You almost certainly will not get away with it.