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