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