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