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