One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(14,19)(15,21)(17,25)(20,26)(22,27)(24,28) involution — undirected(2,4)(5,6,8,9)(7,10,11,12)(13,14)(15,18)(16,22)(17,21)(19,25)(20,23)(24,26)(27,28)(6,9)(7,11)(13,15,18,14)(16,20,23,22)(17,19,25,21)(24,27,28,26)(5,7)(6,10)(8,11)(9,12)(13,16,18,23)(14,20,15,22)(17,24,25,28)(19,26,21,27)(6,9)(7,11)(16,23)(20,22)(24,28)(26,27) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.