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