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