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