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