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