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