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