One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(6,7)(9,10)(11,18)(12,26)(13,28)(14,20)(15,22)(16,21)(17,24)(19,31)(23,38)(25,34)(27,33)(29,40)(30,37)(32,36)(35,39) involution — undirected(1,2,4,5)(3,7,8,6)(9,11)(10,17)(12,16)(13,29)(14,24)(15,25)(18,20)(19,35)(21,34)(22,26)(23,30)(27,31)(28,38)(32,39)(33,36)(37,40)(9,12,15,11,14,25,16,24)(10,18,21,26,20,17,22,34)(13,27,31,23,30,39,32,29)(19,35,28,38,36,33,37,40)(1,3,4,8)(2,6,5,7)(9,13,14,30)(10,19,20,36)(11,23,24,29)(12,27,25,39)(15,31,16,32)(17,33,18,35)(21,28,22,37)(26,38,34,40)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.