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