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