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