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