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