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