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