I have a 3 prong dryer with 4 prong outlet on wall—is there a wiring diagram to switch the outlets on the wall?

You should change the cord on the dryer to a 4-prong cord. It will provide the proper grounding of the appliance. Most driers require moving a white wire from the chassis of the drier to the common terminal inside the drier and then attaching the ground wire from the cord directly to the chassis. You should be able to view an installation manual for your specific brand and model from the manufacturer's website. This will have the instructions for properly replacing the cord. If you are not comfortable replacing it yourself, then consult a qualified appliance repair person. If it is not done correctly, there is a great risk of electrocution or fire.