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)(11,14)(12,17)(13,16)(15,20)(18,22)(19,24)(21,23)(25,26,31,33)(27,35,29,32)(28,34,38,39)(30,36,40,37)(3,7)(5,8)(9,10)(11,14)(12,15)(13,16)(17,20)(18,22)(19,23)(21,24)(25,27,31,29)(26,32,33,35)(28,37,38,36)(30,34,40,39)(1,2)(3,5)(4,6)(7,8)(10,11)(15,17)(16,18)(23,24)(26,33)(28,38)(32,35)(36,37) involution — undirected(1,3,4,7)(2,5,6,8)(9,11,14,10)(12,17,20,15)(13,16,22,18)(19,23,21,24)(25,28)(26,34)(27,36)(29,37)(30,32)(31,38)(33,39)(35,40)(1,2)(3,5)(4,6)(7,8)(9,12)(10,15)(11,17)(13,21)(14,20)(16,24)(18,23)(19,22)(25,29,31,27)(26,35,33,32)(28,37,38,36)(30,34,40,39)(9,13)(10,16)(11,18)(12,19)(14,22)(15,23)(17,24)(20,21)(25,30,31,40)(26,36,33,37)(27,34,29,39)(28,35,38,32)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.