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