How does one control the color of sketches shown in a part file?
When editing a sketch in a part file, the colors are defined in the Solid Edge Options> Colors tab, this is well known, but when you are not editing a sketch, the color the sketch shows while displayed is controlled by the Construction Default face style.
To modify the color (do this in your part template file if you want your new parts to reflect the new color. This will also change the edge color of all construction elements such as surfaces and bodies in the file):
Once you find what you want, just click OK and Apply. All sketches and edges of construction elements s in the file change to the new color.