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