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