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