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)(15,19)(16,21)(17,20)(18,23)(22,26)(24,27)(25,28) involution — undirected(1,2,4,3)(5,7)(6,9)(8,11)(10,12)(13,15,18,16)(14,19,23,21)(17,24,26,25)(20,27,22,28)(1,3,4,2)(7,11)(9,12)(14,20)(17,26)(19,27)(21,28)(22,23)(24,25)(7,11)(9,12)(13,16,18,15)(14,21,23,19)(17,25,26,24)(20,28,22,27)(6,10)(9,12)(15,16)(19,21)(24,25)(27,28) 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.