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