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