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