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