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