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