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