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