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