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