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)(15,24)(16,22)(17,20)(18,19)(21,26)(23,27)(25,28) involution — undirected(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15,16,18)(14,19,22,24)(17,25,26,27)(20,23,21,28)(2,4)(5,8,9,10)(6,7,11,12)(14,20)(15,18)(17,27)(19,28)(21,22)(23,24)(25,26)(6,11)(7,12)(14,21)(15,18)(17,27)(19,23)(20,22)(24,28)(25,26) involution — undirectedA 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.