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