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