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