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