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