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