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