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