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