Firstly, you don't need to set a wire partnumber in VeSys 2.0 Design, this will be automatically selected for you in VeSys 2.0 Harness. As for setting a default wire color & material, this isn't possible however you can multi-select all wires on your diagram (or design, using the design browser) and set the color/material.
I will add your suggestion for a default to our IDEAS database.
PS - I like your avatar
Preferred the picture of the digger to my mug shot - thought a picture of me would put people off!!!