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