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