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