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