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