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