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