Bo Jackson's official 100m time is listed as 10.4, yet claims abound that he ran a 4.12 (or 4.13, according to Bo) 40-yard dash. Given that Christian Coleman, one of the most explosive sprinters in track & field history, has recorded the same time, it seems unlikely that Bo Jackson would even be close to, let alone even with, Coleman at the 40-yard distance.
For reference, Coleman owns the 60m world record: 6.34 seconds.
Coleman's 100m PR is 9.76 seconds.
You'd think that if Bo Jackson were really as fast as he and others contend, he would have been in the mix to represent Team USA at the '84 or '88 Olympics. My suspicion is that Bo Jackson is either exaggerating or misremembering, with the benefit of unreliable reporting.
Bo Jackson is certainly one of the best athletes in history, but these kinds of myths distract from the legitimate achievements of other athletes, such as Bob Hayes, who is still probably the fastest player in NFL history. Conveniently, Hayes has the numbers and medals to back that up.