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