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