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