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