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