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