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