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