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