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