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