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