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