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