EEVEE only answer!
As it's hard to create such material in Cycles as you posted above, it's fairly easy to achieve it in EEVEE (for now only in Blender 2.8 Alpha 2).
For Cycles answer you can check here: Is there really a way to make a true toon shader material in Cycles? Many nice examples provided.
Node setup and overview.
We are using here Specular BSDF to get simple shading and convert it to colour through Shader to RGB. From it we are making two "channels" for separated highlights and shadow using Color Ramps.
After that we are combining those "channels" with Noise and then mixing them to get final "mask".
At the end we have Color Ramp with our colours. From left: shadow, main and highlight. And connect it to Emission shader.
Optionally you can add some Contrast or Saturation, or anything to improve result.
This is how I would do it in Cycles (Eevee).
Since you need to break up that blue color with spots it better not to use the principled shader. So I just took 2 diffuse nodes with the blue and green color and used a gradient texture with a color ramp to control to fall off.
Mix that together with a glossy node for the shine. (If you want to take the shine off, connect the 2nd mix shader directly to the output ("no gloss")).
Then play with all the nodes I circled. Those will control how big the spots are and how you want the falloff to look.
Hope this helps a little.
This one I just added a bump node (circled) to give you the bumpy look if thats what you are after.