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