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)(15,21)(16,27)(17,22)(18,23)(19,24)(20,25)(26,28) involution — undirected(1,2)(3,4)(6,10)(11,12)(13,15)(14,21)(16,20)(17,18)(19,26)(22,23)(24,28)(25,27) involution — undirected(5,7,9,8)(6,11,10,12)(13,16,18,17,20,15,19,26)(14,22,24,27,25,28,23,21)(2,4)(5,8,9,7)(6,12,10,11)(13,17,18,15,20,26,19,16)(14,21,24,22,25,27,23,28)(6,10)(11,12)(13,18,20,19)(14,23,25,24)(15,17,16,26)(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.