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