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