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