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