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