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