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