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