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