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