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