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