Somewhere in my pile of notes is a notepad with ideas on different breeds of Mind Flayers based on the different Psionic Classes.
The basic Mindflayer is the telepathic one, but now imagine a mind flayer with a more squid-like head with the arrowhead frill, he is the Seer of the Mindscape. They are the "priests" of the Mindflayer comunity.
Now conisder the Mindflayer you do not see, because he is camoflagued by his chameleon ability, he is the Egoist and can extend his tentacles to where you are standing.
Next comes a mindflayer covered with a mucous layer of ectoplasm, he is the Shaper and you will never get close to him before his Constructs attack.
Now before you is a mindflayer wearing goggles and wrapped in leather and bandages, he is the Nomad and occationally his teleports go to sunny places, so he has to be prepared.
Lastly, there is a smaller mindflayer with short tentacles crackling with energy, he is the Kineticist and is about to unleash hell under earth on you.
Remember that Mindflayer reproduce by way of Ceremorphosis, conversion of another humanoid, so that humanoid could influence the final form. You could have a muscular, Psychic Warrior flayer from a Hobgoblin or a small Lurk from a Halfling.
That might be interesting, what if the Mindflayer was a template added to the creature that was ceremorphed?