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