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