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