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