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