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