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