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