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