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