If a brep doesn’t shade when displayed by a standard Grasshopper object, then that’s a bug. In fact we found and fixed a bug a couple of weeks ago where all subsequent breps would go unshaded, so it could well be that. What version of Rhino are you on?
The colour however is another matter altogether. Geometry in GH doesn’t come with any attributes like Rhino geometry does. No layer, no name, no colour, no dash style… just pure geometry. You cannot ‘make’ an object blue in Grasshopper. Instead, the colour of the preview is almost always a function of the selected state of the object that contains it. Selected=green, Unselected=red by default, but these can be changed.
Only certain objects draw geometry in non-standard colours, the most famous of these is the Custom Preview component whose entire purpose is to draw things differently.