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