One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,10)(8,12)(9,11)(14,18)(19,26)(20,25)(24,27) involution — undirected(2,4)(5,7,9,8)(6,10,11,12)(14,19)(16,23)(17,22)(18,26)(20,27)(21,28)(24,25)(5,8,9,7)(6,10,11,12)(13,14)(15,18)(16,24)(17,25)(19,23)(20,22)(21,27)(26,28)(2,4)(14,18)(19,26)(20,25)(24,27) 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.