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