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