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