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