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