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