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