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