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)(11,18)(12,20)(13,15)(14,16)(17,21)(19,23)(22,24)(26,32)(27,28)(34,37)(35,36)(2,5)(6,7)(9,11,15,14)(10,16,13,18)(12,19,21,22)(17,23,20,24)(25,26)(27,33)(28,30)(29,37)(31,32)(34,39)(35,38)(36,40)(1,2)(3,6)(4,5)(7,8)(25,27,31,28)(26,33,32,30)(29,35,39,36)(34,40,37,38)(1,2)(3,6)(4,5)(7,8)(9,12)(10,17)(11,19)(13,20)(14,22)(15,21)(16,23)(18,24)(25,28,31,27)(26,33,32,30)(29,36,39,35)(34,40,37,38)(1,3,4,8)(2,6,5,7)(9,13,15,10)(11,16,14,18)(12,20,21,17)(19,23,22,24)(25,29)(26,34)(27,35)(28,36)(30,38)(31,39)(32,37)(33,40)(9,14,15,11)(10,16,13,18)(12,19,21,22)(17,24,20,23)(25,30,31,33)(26,28,32,27)(29,38,39,40)(34,36,37,35)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.