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