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