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