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