I think you might need to check with local Artists. Or maybe check local Pediatric locations - Hospitals, Surgeons, Doctors Offices to see if they've had anyone do this.
I'm a big fan of posting requests like this on local town forums. You can get good recommendations for things.
I did a google image search for "southern california local artists children's wall murals" and found a link to this one:
http://www.allmyheartonline.com/childrens-rooms.html
Keep searching! You might even check with the local High Schools Art Teachers to see if they recommend one of their Students. There's a lot of talent out there. Best wishes!