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