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