I'm sure this is quite easy but can't seem to figure it out , how can I get my primitive object color into the Mantra shading network so that I can use it to control a mix map?

I managed to get it!
For those that would benefit from knowing I just added a “shading layer parameter” node inside the material builder node and it takes in the Cd attribute really well, previously I was trying to using import attribute in just the material network and it didn't work.

promote Cd to points in geometry. And in material use bind and read Cd attribute, configure bind to vector or 3 floats and connect as you want.

Thank you Malkrus! that's good info

If you want to keep your primitives colored and kept the colours not bleeding between the primitives then you should promote Cd to vertex attributes.