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