In terms of "gender" as humans experience it in general, there really wouldn't be one. In terms of masculine/feminine personality traits, you could argue that certain traits would be beneficial in cybertronians geared towards certain tasks. This would require deliberate control over the personalities of cybertronian during manufacturing, however. In the fiction, there are far more examples of personality traits that are superfluous, or even detrimental, to the tasks assigned to given characters than there are synergetic traits, I would say. It's possible that the origins of personalities in cybertronians are just as nebulous as in humans, or possibly even moreso given the lack of biological motivators present in humans.