A wizard looks however I want it to look given the context of their world, specific magic system, and the character's own background. In most cases, it probably involves some kind of spellbook, but the spellbook can be tattoos, a magical tablet floating behind them, an actual book, a scroll case, etc. I'm also always looking to expand my visual vocabulary of concepts. If someone shows me something I hadn't expected and calls it a wizard, then my visual vocabulary has expanded. I prefer to be open-minded in this case, not close-minded, close-minded perspectives themselves being the antithesis of good art.