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