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