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