If you're not up to speed yet with seeing the signs and symbols of the Angels around you, here's a fantastic case study: the official music video of Don't You Worry by the Black Eyed Peas, Shakira, and David Guetta.
2 of Aza's symbols and an M.
Aza's colours (black and red) and Karistus colours (blue and white).
X is a sign of the Karistus.
James Rink from the SSP Super Soldier Talk says they teach sign language to the human and alien personnel in places like area 51 to help facilitate communication.