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