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