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