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