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