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