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