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