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