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