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