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