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