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