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