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