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