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