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