Enums (or named constants if you don't have enums) and switch statements (or if you don't have these, make a hashmap of state->method or something) are all you need. I'm not sure I get what you mean.
One of the primary features of state machines is that state transitions are well-defined. "Describing state machines", as the GP said, is typically done with tools like a reachability matrix or truth table. A looped switch statement will allow you to implement a state machine, but not describe it.
In other words, how would you express in code: "state Z can only be entered through either state W or X, but not through state Y", or "state V must be followed by state W, but only after condition A"? Sure, you can write a switch statement. But half the rules of a state machine can only be implemented by omission (i.e. by not coding it, instead of hardcoding the requirements).
