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