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