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