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