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