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)(12,23)(13,17)(14,18)(15,22)(16,21)(20,24)(25,26)(27,33)(28,32)(29,30)(31,35)(34,39)(36,37)(38,40)(2,7)(3,4)(9,11)(10,15)(12,20)(13,21)(14,22)(16,24)(17,23)(18,19)(26,30)(31,33)(32,37)(38,39) involution — undirected(1,3,6,4)(2,8,7,5)(9,10,14,18)(11,15,22,19)(12,16,21,23)(13,17,20,24)(25,26)(27,31)(28,32)(29,30)(33,35)(34,38)(36,37)(39,40)(1,4,6,3)(2,5,7,8)(9,10)(11,19)(12,16)(13,24)(14,18)(15,22)(17,20)(21,23)(25,27,29,35)(26,31,30,33)(28,34,36,40)(32,38,37,39)(1,5)(2,3)(4,7)(6,8)(9,12)(10,16)(11,20)(13,22)(14,21)(15,24)(17,19)(18,23)(25,28,29,36)(26,32,30,37)(27,34,35,40)(31,38,33,39)(9,13,14,20)(10,17,18,24)(11,21,22,12)(15,23,19,16)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.