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