What did the Big Bang look like?

Prior to the Big Bang, the universe was just one massive singularity that held all of the mass in the universe. Somehow, the singularity separated into atoms and other particles—likely due to dark energy—and eventually gave rise to the universe as we know it today. The exact nature of this separation is unknown, but it can be conceptualized as if the singularity itself had broken into trillions of tiny particles that eventually made up the universe.

...at least for the first 380,000 years or so. During that time, photons could not go very far because the universe was an opaque plasma.

The Big Bang itself is a theoretical concept that describes the universe's rapid expansion from a hot, dense state; it was not a visual event because no observers were present to witness it. The Big Bang's early moments were probably filled with intense radiation and high-energy particles, but light wouldn't have existed until the universe cooled down enough for atoms to form and light could travel freely.