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