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