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)(15,19)(16,21)(17,26)(18,22)(20,23)(24,28)(25,27) involution — undirected(1,2)(3,4)(5,6)(7,11)(8,10)(9,12)(13,15,18,17)(14,19,22,26)(16,24,25,23)(20,21,28,27)(5,7,8,12)(6,9,10,11)(13,16,18,25)(14,20,22,28)(15,23,17,24)(19,27,26,21)(2,4)(7,12)(9,11)(13,16)(14,21)(15,24)(17,23)(18,25)(19,28)(20,26)(22,27) involution — undirected(6,10)(9,11)(14,22)(16,25)(19,26)(23,24) 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.