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