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