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