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