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