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)(11,22)(12,18)(13,19)(14,30)(15,20)(16,21)(17,25)(23,39)(24,32)(26,34)(27,36)(28,37)(29,33)(31,35)(38,40) involution — undirected(9,11,14,25,16,26,15,31)(10,17,20,22,21,35,30,34)(12,24,13,29,27,40,28,23)(18,33,37,32,36,39,19,38)(2,5)(6,8)(9,12,14,13,16,27,15,28)(10,18,30,19,21,36,20,37)(11,23,31,40,26,29,25,24)(17,32,22,39,35,38,34,33)(9,13,14,27,16,28,15,12)(10,19,30,36,21,37,20,18)(11,24,31,23,26,40,25,29)(17,33,22,32,35,39,34,38)(1,3,4,7)(2,6,5,8)(12,27)(13,28)(18,36)(19,37)(23,29)(24,40)(32,38)(33,39)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.