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