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