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