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