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