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