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