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