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