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)(27,32)(28,37)(29,36)(30,35)(31,33)(34,38)(39,40)(1,3,5,8)(2,6,4,7)(25,27)(26,32)(28,30)(29,33)(31,36)(34,40)(35,37)(38,39)(1,2,5,4)(3,6,8,7)(10,15)(11,16)(17,22)(18,23)(26,33)(27,36)(28,38)(35,40)(1,4,5,2)(3,7,8,6)(9,11,14,16)(10,12,15,20)(13,18,21,23)(17,19,22,24)(25,28)(26,34)(27,30)(29,35)(31,38)(32,40)(33,37)(36,39)(9,12)(10,16)(11,15)(13,19)(14,20)(17,23)(18,22)(21,24)(25,29,31,32)(26,27,33,36)(28,35,38,40)(30,37,39,34)(9,13,14,21)(10,17,15,22)(11,18,16,23)(12,19,20,24)(25,30)(26,35)(27,28)(29,34)(31,39)(32,37)(33,40)(36,38)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.