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