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