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