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