Blue is not the only crystal color that Cal can use jedi: Fallen order. He will discover a handful of colors during his trip, but to get there, you have to progress in the game until a certain point.
During Cal’s trip, you will find yourself visiting the planet Ilum. It is there that many Jedi went to receive their Kyber crystals, with whom they have linked by force and were inserted into their lightsaber. These crystals fueled the Jedi weapon, giving it unique colors.
When Cal arrives at the time of the truth to choose his laser lighting color, he can choose a new crystal and has several options.
You have the choice among the eight options. Blue and green are available from the start. If you have pre-order the game, you immediately get orange, as well as green and blue. However, when you come back to the Mantis, all colors are available.