On the wikipedia page of [tetrahedron][1], there is a list of eight symmetry groups for a (possibly irregular) $3$-simplex (with unmarked faces). There is also a list on the page of [5-cell][2] but doesn't seem complete. This seems elementary, but I can not find a source to cite. Also, is there already a general classification for symmetry groups of unmarked (possibly irreglar) d-simplices (or an algorithm for enumerating it)? I believe this is equivalent to asking about the symmetry of edge-colored complete graphs. I find a lot of literature on those with transitive groups, but not general cases. [1]: https://en.wikipedia.org/wiki/Tetrahedron#Isometries_of_irregular_tetrahedra [2]: https://en.wikipedia.org/wiki/5-cell#Irregular_5-cell