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