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