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