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