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