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