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