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