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