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