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