The 4 prong plug is for 2 live wires, a neutral and a case ground. If you choose to obtain a socket to match the plug on the saw you will use the two live wires and the case ground. The wiring in the 4 prong plug if wired correctly should contain one red wire as a live wire, one black wire as the other live wire (220 volts across them), a white wire as the neutral (Not needed in your application) and a bare copper as the case ground. Wire them to the new socket according to the instructions that usually comes with new sockets and you'll be in business.
Don Dando