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