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