One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,8)(5,6)(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(25,26,29,31)(27,32,37,39)(28,38,35,33)(30,34,36,40)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23)(26,31)(27,35)(28,37)(30,36)(32,38)(33,39) involution — undirected(2,6)(7,8)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,27,36,28,29,37,30,35)(26,32,40,38,31,39,34,33)(1,3,5,4)(2,7,6,8)(10,16)(14,17)(15,22)(21,23)(26,31)(27,37)(28,35)(34,40)(1,4,5,3)(2,8,6,7)(11,19)(14,17)(18,24)(21,23)(25,28,36,37,29,35,30,27)(26,33,40,32,31,38,34,39)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.