Blue-and-white highlights the standard Adder colors of black and dark blue on Delta's equipment.
Per FM:Crusader Clans, page 125.
All Adder 'Mechs and fighters bear the Clan insignia on the left arm or wing and right leg or empennage. Galaxy insignias are displayed on the right arms or wings and left legs or empennages, while Cluster insignias are worn on the right torsos of 'Mechs or the fuselages of fighters.
The Galaxy's Insignia is a lightning strike that outlines the shape of a star adder.
Per FM:Crusader Clans, pages 118 and 125.