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