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