The Cybertronians are a faction in the Generation Two part of Generation One continuity
Sigil of the Cybertronian Empire
The Cybertronians were a result of Decepticon experiments in Bio-Morphic Reproduction ("budding") ~4 million years ago on Cybertron. The Decepticons were able to rapidly expand their population using this method, but the newly created Transformers felt no attachment to Cybertron as a homeworld and (apparently en-masse) left to conquer other worlds.
In the modern era, the Cybertronian Empire has conquered many worlds, enslaving or exterminating the native population and cyberforming the planets to create 'little Cybertrons.' Despite their Decepticon descent, Cybertronians do not consider themselves either Autobot or Decepticon.
They do not wear funny hats.
The Cybertronian faction-symbol was also adopted by Bludgeon's Decepticon forces during their period of exile from Cybertron while operating outside of the Milky Way.
It's possible the symbol has a common cultural meaning that would cause two disconnected groups of Decepticons expatriates to gravitate towards it.