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