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