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