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