Layover for 20 hrs in Shanghai from SF/USA to New DELHI/India. Do I need visa to leave airport ?

Hi I hold and Indian passport and OPT work visa for US. On my flight to India I have a 20 hr layover in Pudong,Shanghai. Do I need to get any visa to get out of the airport to see the city ? Is there safe locker service at the airport where I can leave my bags for a few hours ?

Thanks !