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