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