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