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