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