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