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