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