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