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