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