So I had a bit of a sketch re the relay switching and this is what I came up with.
The relays are drawn as individual DPDT switches, with the coil connectors not shown.
The connections from the capsule to the main circuit are labelled A, B and C from top to bottom.
As shown in the previous relay schematic, in the de-energised state there is a connection between the poles and the middle pins. In the energised state there is a connection between the poles and the upper pins.
The switch on the PSU would then need to only supply 2 rails of coil voltage for figure of 8 and omni, with the PSU position for cardioid being no connection.
Am I close?