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