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