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