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