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