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)(25,26,31,35)(27,29,37,32)(28,38,36,33)(30,34,40,39)(2,5)(6,8)(9,11,14,18)(10,13,15,17)(12,20,22,19)(16,21,24,23)(25,27,31,37)(26,32,35,29)(28,30,36,40)(33,34,38,39)(1,2,4,5)(3,6,7,8)(10,15)(11,18)(16,24)(19,20)(25,28,31,36)(26,33,35,38)(27,30,37,40)(29,39,32,34)(3,7)(6,8)(9,12,14,22)(10,16,15,24)(11,19,18,20)(13,23,17,21)(25,27)(26,32)(28,30)(29,35)(31,37)(33,34)(36,40)(38,39)(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)(26,27,35,37)(28,34,36,39)(30,33,40,38)(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)(26,34)(27,36)(28,37)(29,33)(31,40)(32,38)(35,39)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.