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