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)(11,19)(12,13)(14,16)(15,17)(18,23)(20,21)(22,24)(25,26)(27,31)(28,37)(29,33)(30,34)(32,36)(35,40)(38,39)(3,7)(5,8)(9,11,15,14)(10,16,17,19)(12,22,18,20)(13,21,23,24)(25,27,30,35)(26,31,34,40)(28,29,36,39)(32,38,37,33)(1,2)(3,5)(4,6)(7,8)(10,17)(12,18)(16,19)(20,22)(27,35)(28,36)(31,40)(32,37) involution — undirected(1,3,4,7)(2,5,6,8)(9,12,15,18)(10,13,17,23)(11,20,14,22)(16,24,19,21)(25,28)(26,32)(27,29)(30,36)(31,38)(33,40)(34,37)(35,39)(1,2)(3,5)(4,6)(7,8)(9,13)(10,18)(11,21)(12,17)(14,24)(15,23)(16,20)(19,22)(25,26)(27,31)(28,32)(29,38)(30,34)(33,39)(35,40)(36,37) involution — undirected(9,14,15,11)(10,16,17,19)(12,20,18,22)(13,21,23,24)(25,29)(26,33)(27,36)(28,35)(30,39)(31,32)(34,38)(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.