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