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