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