In Judaism, a soul looks sort of like a glowing, fiery cross that lives in the center of our body.
Sort of like a KKK cross burning, without the KKK.
At least, that’s how I always imagined it.
If you think about it, a soul probably doesn’t look like anything. If you could see it, we probably wouldn’t have as many atheists around today.
So at the very least we can agree that it’s invisible. So, another way of answering your question is: what does a soul look like? It looks like a really really clean window.