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