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