You can use cable ties and cable sleeves to organize the cords under your desk. As to the cable ties, there can be standard non-reusable plastic zip ties or reusable plastic zip ties or felt cable wrap ties.
Cable Sleeves can come with a zipper, Velcro, or be self-closing. Self-closing allows for more cables, whereas zippers can be purchased in multiples and used together to create a more extensive sleeve.