Wiring Motor to DPDT Polarity Switch
It is unlikely that the motor is designed to be reversed without first shutting it off and waiting for it to coast to a stop. You need two switches. You need a simple on/off switch to connect and disconnect the power. The second switch is used to reverse the motor by interchanging the red and black lead connections to the "INS" and "L2" groups of wires. That requires a switch similar to the one that you have except that is does not need a center "off" position.

You should probably download the instructions for this motor if you don't have them.