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