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