Why is it Graphite Ranger & Not Gray Ranger?

Gray ranger sounds boring, but Graphite Ranger sounds cooler. Power Rangers usually tries to make their rangers have cooler names like how BoukenSilver was called the Mercury Ranger and how GaoSilver was the Lunar Ranger.

Also, I think they might be going with a slight elemental theme for the names. I mean Cyan became Aqua. They might be trying to use element names that match the colors. Just my speculation.