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