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