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