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