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