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