Just took a quick glance at this thread since I like cyborgs. First, I’d say the upper arms are too short, my elbow is about at the bottom of my rib cage. In your first pics, the elbow is much higher than that.
Yea muscle shapes might help, but on the whole, I think you need to decide what is human, and what is machine. Is only the head and the stomach area human, and the rest a machine? By definition, a cyborg is a human being that is augmented with mechanical parts. So you could make one shoulder/upper arm human, then lower arm & hand machine, for example. Switch it up a bit. Maybe make a hand a human one. I’ve often thought about modelling a female cyborg, and I know how I would do it… I’d model a female human. then just start cutting her body up and replacing it with mechanical parts.
As to mixing it up color wise, think of the mechanical parts as being made up of many different parts. Right now, as I type, I’m seeing the bottom of the last image you posted. I’m looking at the right arm, I see seams in the upper arm covering, I see what look like wires on the inside of the elbow area. I’d color those in black or color each wire a separate color scheme. I’d make the seams in the upper arm covering just a little bit wider, and make it black or dark color. Same thing with the joint between the hand and lower arm, that part isn’t the same material as the outerbody covering is, so it shouldn’t be the same color.
Try adding in skin color the to skin parts, then work form there, and hair color too. Then proceed, what color the body would look nice with the skin color, what color the smaller bits to contrast with the body. Think about her use as well… Utility female cyborg… so what does she do? Clean the house? A maid/house keeper? Might want to think maid/butler sort of color/style.
Just tossing out thoughts…