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