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