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