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