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