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