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