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