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