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