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