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)(32,37)(35,39)(38,40) 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)(28,35,37,38)(32,39,36,40)(1,3)(2,4)(5,6)(7,8)(10,15)(11,20)(17,24)(18,21)(28,37)(32,36)(35,38)(39,40) involution — undirected(3,6)(4,8)(9,11)(10,16)(12,18)(13,17)(14,20)(15,19)(21,22)(23,24)(25,28)(26,32)(27,35)(29,38)(30,37)(31,39)(33,36)(34,40) involution — undirected(1,4,5,8)(2,6,7,3)(9,12,14,22)(10,17,15,24)(11,21,20,18)(13,16,23,19)(25,26)(27,31)(28,36)(29,34)(30,33)(32,37)(35,40)(38,39)(1,2)(3,4)(5,7)(6,8)(9,13,14,23)(10,18,15,21)(11,17,20,24)(12,19,22,16)(25,29,30,27)(26,31,33,34)(28,38,37,35)(32,39,36,40)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.