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