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