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