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