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