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