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)(25,26)(27,33)(28,38)(29,31)(30,34)(32,35)(36,40)(37,39) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11,15,21)(10,16,17,20)(12,22,23,14)(13,24,18,19)(25,27,32,29)(26,33,35,31)(28,37,30,36)(34,40,38,39)(2,5)(6,8)(10,17)(11,21)(12,23)(19,24)(25,28,32,30)(26,34,35,38)(27,36,29,37)(31,40,33,39)(3,7)(6,8)(9,12)(10,18)(11,22)(13,17)(14,21)(15,23)(16,19)(20,24)(25,29,32,27)(26,31,35,33)(28,36,30,37)(34,39,38,40)(1,3)(2,6)(4,7)(5,8)(9,13,15,18)(10,12,17,23)(11,19,21,24)(14,20,22,16)(25,30,32,28)(26,34,35,38)(27,37,29,36)(31,40,33,39)(1,2)(3,6)(4,5)(7,8)(9,14,15,22)(10,19,17,24)(11,12,21,23)(13,20,18,16)(25,31)(26,27)(28,39)(29,35)(30,40)(32,33)(34,37)(36,38)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.