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