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)(13,14,16,26,17,19,18,21)(15,22,24,20,23,28,25,27)(2,3)(5,6)(7,11)(8,10)(9,12)(14,19)(15,23)(21,26)(24,25) involution — undirected(5,7,8,12)(6,9,10,11)(13,15)(14,20)(16,25)(17,23)(18,24)(19,27)(21,28)(22,26)(1,3,4,2)(7,12)(9,11)(13,16,17,18)(14,21,19,26)(15,24,23,25)(20,22,27,28)(6,10)(9,11)(13,16,17,18)(14,21,19,26)(15,25,23,24)(20,28,27,22)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.