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