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