You can take them to Nevada or any other State where they are legal and sell them, but the transfer will have to go through an FFL. So you and the buyer would meet at an FFL in the other State and do the transfer. The FFL is going to charge a fee for this service and some FFLs don't like to do any transfers that involve a Californian.
Another option if you find a buyer from another State is to have a California licensed dealer who also has an assault weapons permit ship the gun to the out of state buyer's local FFL. In this case both FFLs will charge something.