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