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