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