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