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