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