Oooh, Pretty Colors!
Wondering why you're not getting XP? Are you suffering from insta-death or mowing down NPCs like crazy?
Missions are color coded so you can check that out!
Gray: You are five or more levels over the mission. It will make you feel like Superman, but you won't get any XP.
Green: You are slightly over leveled. Piece of cake.
Yellow: You are at level, or maybe one over, the mission. You might die. This is normal!
Orange: This mission is 3-5 levels above you. You will probably die.
Red: Five or more levels over you. You will definitely die.
Color coding is also present on Resource Nodes. Gray = no points, Red = Unable to harvest, orange will give the most points, yellow some points, and green the least amount of points. Same with crafting schematics and crew missions.