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