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