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