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