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