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