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