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