Once you plan on taking the left, make sure to set aside enough time to explore. Because the pull-out is on the other side of the road, it actually makes parking easier if you go beyond the cave and explore El Camino Cielo.
In Spanish, El Camino Cielo means "The Sky Road". From this vantage point, you have the sandstone mountains rising up all around you. Peer out to the west, on a clear day, and you can see the Channel Islands. Look out to the panorama of the horizon, and you will notice the earth is truly curved. There are several points along El Camino Cielo to stop along the road and take in a new view. Stop. Get out. Breathe in the air. On the right day, simply being in the moment can be a religious experience.
Once you have soaked in all the scenery from the top, it's time to go see some history.
Be aware that the parking situation is tight (in the very least). Please be considerate when parking, and try to maximise all the space they've provided.
The trail from the road has a few short stairs, but isn't very long or steep (you will probably see the people above you, as you park). The "paintings" on these sandstone walls, more than likely, depict some sort of cosmology.
I'm fascinated by ancient cultures. Throw in the appeal of some wheels and arrows, drawn on a wall close to 1000 years ago.....and I'll take a day to check them out! Plan to go witness them yourself, and come up with your own theories on what the spokes of the wheels represent. What do you think?