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