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