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