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)(11,13)(12,20)(14,16)(15,18)(17,22)(19,21)(23,24)(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)(10,15)(12,19)(13,16)(14,18)(17,21)(20,23)(22,24)(25,27,30,29)(26,31,33,34)(28,35,38,37)(32,39,36,40)(10,16)(11,18)(17,20)(19,24)(25,26)(27,34)(28,32)(29,31)(30,33)(35,40)(36,38)(37,39) involution — undirected(1,4,5,2)(3,7,8,6)(9,11)(10,15)(12,19)(13,16)(14,18)(17,21)(20,23)(22,24)(25,28,30,38)(26,32,33,36)(27,35,29,37)(31,39,34,40)(9,12,14,22)(10,17,16,20)(11,19,18,24)(13,23,15,21)(25,26)(27,31)(28,32)(29,34)(30,33)(35,39)(36,38)(37,40)(9,13,14,15)(10,11,16,18)(12,21,22,23)(17,24,20,19)(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.