In order for you to have the correct colors of mechanisms, I advise you open the game directory, go to this path .minecraft\config\gregtech open the file "gregtech.cfg" 
and there in the item "The default color to overlay onto machines", and next to the inscription "defaultPaintingColor" change the number from 13819135 to 16777215, 
this will disable the standard filter that makes the textures for mechanisms with a blue tint, in the case of my textures, I would recommend doing this so that you see the color of the textures as I designed it. 
You can also optionally do the same in "The default color to overlay onto Machine (and other) UIs.", then the Gregtech mechanism interface will no longer be blue, but that's up to your taste, but I would personally disable it.
                                                                                                                                                                           ILAORE
