Based on the clear V shape they're going for to signify 5, with the black in the middle surrounded by white, I'm a little surprised the controller didn't end up two toned in a layout more like this.
The touch pad being in a V shape is almost certainly to keep with the 5 reference, so why they didn't make it black to better match the console's overall scheme I dunno. Maybe that was seen as to easy or to simple? White triggers would also match the console better, but I don't think that would look as good on the controller. I'm not a big fan of this mock up or the revealed controller color layout anyway, just found it kinda odd why they chose the color layout on the controller that they did, now knowing what the console looks like.