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