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