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