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