It's hard to tell from the photos, but it looks like the cable has a USB A connector on one end, and a "coaxial" power connector on the other end.
If that is the case, then my interpretation of what is going on is that the BOB is using the board-mounted USB connector as a 5-volt DC input connector.
If that is correct, then you can either:
use a standard USB cable (with type A connectors on both ends), plugging in one end to the BOB and the other to a PC's USB connector
- or -
plug the USB A connector of the cable shown in the photo into the USB connector on the BOB, and plug the coaxial power connector on the other end into a "wall wart" 5-volt DC adapter (or other 5-volt DC power supply) that has a mating "female" coaxial power connector. Before doing that, I would carefully verify that the polarity of the power supply connector puts the proper polarity onto the USB connector.