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