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