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