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