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