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