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