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