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