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