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