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