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