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