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