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