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