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