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)(11,12)(13,21)(14,15)(16,23)(17,18)(19,22)(20,24)(25,26)(27,33)(28,32)(29,37)(30,31)(34,38)(35,39)(36,40)(3,7)(5,8)(9,11)(10,12)(13,19)(14,17)(15,18)(16,20)(21,22)(23,24)(26,31)(32,33)(34,37)(39,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(10,15)(11,17)(16,21)(19,24)(25,27,30,28)(26,32,31,33)(29,35,38,36)(34,39,37,40)(9,12)(10,11)(13,22)(14,18)(15,17)(16,24)(19,21)(20,23)(25,28,30,27)(26,33,31,32)(29,35,38,36)(34,39,37,40)(1,3)(2,5)(4,7)(6,8)(9,10)(11,18)(12,17)(13,16)(14,15)(19,22)(20,24)(21,23)(25,26)(27,33)(28,32)(29,34)(30,31)(35,40)(36,39)(37,38) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,13)(10,16)(11,19)(12,20)(14,23)(15,21)(17,24)(18,22)(25,29,30,38)(26,34,31,37)(27,35,28,36)(32,39,33,40)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.