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