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