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