>a^4 = b^2 = 1, a^3 b = ba >has exactly eight elements
I suppose the missing issue (or at least the one I feel could have had more sunshine on it) is how and why elements of the monster groups are represented as this would more subtly capture the symmetry that keeps the group finite. It's not so much symmetry as a subject unto itself, as the subtle interplay between group operations on the form of elements with symmetry that keeps the group finite.
Your term "a^4=1" has exactly that missing emphasis: take element 'a' (i.e. a square) and rotate it four times and it's the same as multiplying a by 1, which is the identity element. Ditto b^2: perform the mirror operation twice and again it's the same as doing b*1 etc.