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