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