The 5th paints their machines white with dark blue stripes along the arms and legs of their BattleMechs.
Per FM:Draconis Combine, page 90.
Every ‘Mech carries the House Kurita crest on its upper left torso. The Sun Zhang Cadres insignia, a setting sun, appears in a different location depending on the cadre. The Fifth Cadre has its own regimental insignia, though any cadre ‘Mech may carry a banner with the cadre name on it. BattleMechs of the Fifth Sun Zhang display the Sun Zhang insignia on the upper right leg. All officers must fly the Fifth Cadre banner from their machines. The regimental insignia, a katana piercing an anvil is displayed on the back of each unit BattleMech. Per FM: Draconis Combine, pages 89 and 90.