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