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