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