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