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