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