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