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