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