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