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