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