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