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