For this test harness, the following datasheets were used RFDesign RFD900x and Pixhawk Baseboard Ports - Holybro Docs . Go to page 7 for RFDesign to check the pinout diagram. The PIXHAWK datasheet explains the ports and their corresponding pins.
The colours on the side represent the wire colours on the harness itself. MAKE SURE you follow these colours if you use this harness otherwise it will not work.