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