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