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