The photo is likely referencing the costume that debuted after the "Death of Superman" storyline in the comics, which saw the Man of Steel killed at the hands of Doomsday -- just as he was in "Batman v Superman." Dan Jurgens created the suit upon the character's revival for "Return of Superman."
"Justice League" director Zack Snyder previously expressed interest in having Superman rock the long-haired look -- which made its debut with the black costume -- so it wouldn't be too much of a stretch to predict the classic Superman look making an appearance (in some form) as a nod to the comics.
Check out Cavill's post below:
Directed by Zack Snyder, "Justice League" hits theaters on November 17, 2017.