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